N,N-dimethylformamide--influence of working conditions and skin penetration on the internal exposure of workers in synthetic textile production.

Abstract

This study examined the external and internal exposure to the solvent N,N-dimethylformamide (DMF) of 126 workers from a factory producing synthetic fibers. Air measurements were carried out using personal air samplers with diffusion tubes (Drager, ORSA 5). For the purpose of biological monitoring the levels of N-methylformamide (NMF) in urine were measured in preshift and postshift samples. Determinations were carried out using gas chromatography. Anamnestic data were collected with standardized questionnaires, including personal data, working history and current working conditions, and former and current illness with regard to the effects of DMF. Skin diseases were documented by a dermatologist. DMF concentrations measured in the air ranged between <0.1 and 37.9 ppm (median 1.2 ppm). Concentrations of NMF varied from 0.05 to 22.0 mg/l (preshift values) and from 0.9 to 100.0 mg/l (postshift values). The creatinine-related values (0.02-44.6 mg/g preshift; 0.4-62.3 postshift) were subject to less variation and therefore represented the level of exposure better than the values related to volume. Additional investigation of a subcollective (n=31) over a period of 4 days showed that NMF did not accumulate in the organism. The positive but relatively weak association observed between the DMF concentrations measured in the workplace air and the values recorded for internal exposure in this study can be explained by influencing factors such as dermal absorption or protective clothing. Interindividual differences in internal exposure were found for the specific work areas. The German BAT value (15 mg NMF/l urine) was exceeded in 36 persons (29%) despite the use of breathing protection and protective gloves, without increased values being measured in the air. Increased absorption without higher-level exposure could particularly also be observed in employees with eczema. From the point of view of the prevention of disease, biological monitoring is the best instrument for exposure assessment of workers exposed to DMF.